Indian Ocean

Indian Ocean, the smallest of the earth's three great oceans, bounded on the west by Africa, on the north by Asia, on the east by Australia and the Australasian islands, and on the south by Antarctica. No natural boundary separates the Indian Ocean from the Atlantic Ocean, but a line about 4020 km (about 2500 mi) long on the 20th meridian east of Greenwich, connecting Cape Agulhas at the southern end of Africa with Antarctica, is generally considered to be the boundary. The total area of the Indian Ocean is about 73.4 million sq km (about 28.3 million sq mi). The ocean narrows toward the north, and is divided by the Indian peninsula into the Bay of Bengal on the east and the Arabian Sea on the west. The Arabian Sea sends two arms northward, the Persian Gulf and the Red Sea. The average depth of the Indian Ocean is about 4210 m (about 13,800 ft), or slightly greater than that of the Atlantic, and the deepest known point is about 7725 m (about 25,344 ft), off the southern coast of the Indonesian island of Java. In general, the greatest depths are in the northeastern sector of the ocean, where about 129,500 sq km (about 50,000 sq mi) of the ocean floor lie at a depth of more than 5486 m (18,000 ft). The Indian Ocean contains numerous islands, the largest of which are Madagascar and Sri Lanka. Smaller islands include the Maldive group and Mauritius. From Africa the ocean receives the waters of the Limpopo and Zambezi rivers, and from Asia those of the Irrawaddy, Brahmaputra, Ganges, Indus, and Shatt al Arab rivers. As a rule, the winds over the Indian Ocean are gentle, with frequent extended periods of calm. Tropical storms occur occasionally, however, particularly near Mauritius, and the ocean is notable for seasonal winds called monsoons.